An enhanced time synchronization protocol in automated surface vehicles

Abstract

Mobility of an autonomous surface vehicle (ASV) has caused the wireless sensor and actuator networks (WSANs) onboard to be mobile as well. However, the time synchronization of a WSAN on ASV is more challenging due to the environmental harshness and node mobility. In this paper, an enhanced control-theoretic distributed time synchronization protocol called Time Synchronization using Distributed Observer algorithm with Sliding mode control element (TSDOS) is presented to solve the time synchronization issue in ASV. This TSDOS protocol feeds a sliding mode control element on the relative comparative error to estimate the skew rate and relative skew rate. Through the theoretical analysis and simulations, TSDOS has showed the advantages of totally distributed, robust to node failure and time-varying clock frequencies, which are the situations usually faced by an ASV. In addition, TSDOS also has better or comparable performance over existing protocols in terms of rate of convergence, consensus error spike, and steady-state error.